Method for measuring interference to CM, apparatus, and system

ABSTRACT

The present disclosure provides, for example, methods for measuring interference to a cable modem (CM), and corresponding example apparatuses and systems. One example method includes sending, by a cable modem termination system (CMTS), a broadcast message to all CMs connected to the CMTS, where the broadcast message includes information designating one of the CMs to send a probing signal by using a spectrum S in a timeslot T. The CMTS can then broadcast a pseudo random binary sequence (PRBS) by using the spectrum S in a downlink direction in the timeslot T, and can obtaining modulation error ratio (MER) information recorded in the timeslot T by other CMs. A difference between MER information in the timeslot T and MER information in a normal data timeslot can be used, for each of the other CMs, as intensity of interference to the corresponding CM.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2016/095286, filed on Aug. 15, 2016, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to the communications field, and inparticular, to a method for measuring interference to a cable modem(CM), an apparatus, and a system.

BACKGROUND

The communications field is mainly related to time division duplex(TDD), frequency division duplex (FDD), and co-time co-frequency fullduplex (CCFD).

In a current CCFD solution, CCFD is implemented only on a CMTS side, andon a CM side, all CMs may be grouped based on an interferencerelationship (also referred to as isolation) between the CMs.Specifically, CMs that interfere with each other or have mutualinterference that does not meet a requirement are grouped into a groupto implement FDD within a CM group, and CMs that do not interfere witheach other or have mutual interference that meets a requirement aregrouped into different groups. CCFD is implemented between groups toimprove spectral efficiency.

It may be learned from the foregoing that CM grouping is mainlyimplemented based on an interference relationship between CMs. In otherwords, the interference relationship between CMs can determine CMgrouping. How to obtain an accurate interference relationship betweenCMs is always an issue studied in the industry.

SUMMARY

According to a method for measuring interference to a cable modem, anapparatus, and a system provided in the present invention, a moreaccurate interference relationship between CMs can be obtained.

According to a first aspect, the present invention provides a method formeasuring interference to a cable modem CM, including:

sending, by a cable modem termination system CMTS, a broadcast messageto notify all CMs connected to the CMTS, where the broadcast messageinstructs one of the CMs to send a probing signal by using a spectrum Sin a timeslot T, and the spectrum S is one of overlapping parts betweenuplink and downlink spectrums;

in the timeslot T when the designated CM sends a probing signal by usingthe spectrum S in the timeslot T, broadcasting, by the CMTS, a pseudorandom binary sequence by using the spectrum S in a downlink direction;and

obtaining, by the CMTS, modulation error ratio MER information recordedin the timeslot T by other CMs, and using a difference between MERinformation in the timeslot T and MER information in a normal datatimeslot, of each of the other CMs, as intensity of interference to thecorresponding CM, where the other CMs are CMs remaining after thedesignated CM is removed from all the CMs connected to the CMTS, and thenormal data timeslot is a timeslot in which the CMTS sends service datain the downlink direction.

In a possible design, the method further includes: grouping, by the CMTSbased on the obtained intensity of interference to each of the otherCMs, a CM undergoing interference whose intensity is higher than athreshold and the designated CM into a group.

According to a second aspect, an embodiment of the present inventionprovides a method for measuring interference to a cable modem CM,including:

sending, by a cable modem termination system CMTS, a broadcast messageto ungrouped cable modems CMs, where the broadcast message instructs oneof the ungrouped CMs to send a probing signal by using a spectrum S′ ina timeslot T′, and the spectrum S′ is one of overlapping parts betweenuplink and downlink spectrums;

in the timeslot T′ when the designated CM sends a probing signal byusing the spectrum S′, broadcasting, by the CMTS, a pseudo random binarysequence by using the spectrum S′ in a downlink direction; and

obtaining, by the CMTS, modulation error ratio MER information recordedin the timeslot T′ by non-designated CMs in the ungrouped CMs, and usinga difference between MER information in the timeslot T′ and MERinformation in a normal data timeslot, of each of the other CMs, asintensity of interference to the corresponding CM, where the other CMsare CMs remaining after the designated CM is removed from the ungroupedCMs, and the normal data timeslot is a timeslot in which the CMTS sendsservice data in the downlink direction.

In a possible design, the method further includes: sending, by thedesignated CM, a probing signal by using the designated spectrum S′ inan uplink direction in the timeslot T′.

In a possible design, the method further includes: grouping, by the CMTSbased on the obtained intensity of interference to each of the otherCMs, a CM undergoing interference whose intensity is higher than athreshold and the designated CM into a group.

In a possible design, the CMTS determines, based on configurationinformation of each CM, whether the CM belongs to the ungrouped CMs.

According to a third aspect, an embodiment of the present inventionprovides a cable modem termination system CMTS, including a sendingmodule, a processing module, and a receiving module, where

the sending module is configured to send a broadcast message toungrouped cable modems CMs, where the broadcast message instructs one ofthe ungrouped CMs to send a probing signal by using a spectrum S′ in atimeslot T′, where the spectrum S′ is one of overlapping parts betweenuplink and downlink spectrums; and is further configured to broadcast apseudo random binary sequence by using the spectrum S′ in a downlinkdirection in the timeslot T′;

the receiving module is configured to receive modulation error ratio MERinformation recorded in the timeslot T′ by other CMs; and

the processing module is configured to use, based on the MER informationrecorded in the timeslot T′ by the other CMs and obtained by thereceiving module, a difference between MER information in the timeslotT′ and MER information in a normal data timeslot, of each of the otherCMs, as intensity of interference to the corresponding CM, where theother CMs are CMs remaining after the designated CM is removed from theungrouped CMs, and the normal data timeslot is a timeslot in which theCMTS sends service data in the downlink direction.

In a possible design, the CMTS further includes a grouping module,configured to group, based on the intensity, obtained by the processingmodule, of interference to each of the other CMs, a CM undergoinginterference whose intensity is higher than a threshold and thedesignated CM into a group.

In a possible design, the processing module is further configured todetermine, based on configuration information of each CM, whether the CMbelongs to the ungrouped CMs.

According to a fourth aspect, the present invention further provides acable modem CM, including a sending module, a receiving module, and arecording module, where

the receiving module is configured to receive a broadcast message sentby a CMTS, where the broadcast message includes information designatingthe CM to send a probing signal by using a spectrum S in a timeslot T,and the spectrum S is one of overlapping parts between uplink anddownlink spectrums; and is further configured to receive, by using thedesignated spectrum S in the designated timeslot T, a pseudo randombinary sequence PRBS sent by the CMTS;

the sending module is configured to send a probing signal by using thedesignated spectrum S in the designated timeslot T based on thebroadcast message received by the receiving module; and

the recording module is configured to: record a local MER when a probingsignal is sent by using the designated spectrum S in the designatedtimeslot T, and record a local MER in a normal data timeslot.

In a possible design, the sending module is further configured to sendthe MER information recorded by the recording module to the CMTS.Alternatively, the sending module sends a difference between the MERinformation in the timeslot T and the MER information in the normal datatimeslot to the CMTS.

According to a fifth aspect, the present invention further provides acable communications system, including the foregoing cable modemtermination system CMTS and the plurality of cable modems CMs.

According to the solutions of the embodiments, one designated CM isrequired to send a probing signal by using a designated spectrum in anuplink direction in a particular timeslot, and at the same time, theCMTS broadcasts a PRBS by using the designated spectrum in a downlinkdirection. This is equivalent to construction of a test environment. Adifference between an MER in the test environment and an MER in a normalservice data receiving and sending environment of each CM reflectsintensity of interference to each CM. In the constructed testenvironment, the CMTS also sends a signal. In this way, measuredintensity of interference to the CM is more accurate.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention more clearly, the following briefly describes the accompanyingdrawings required for describing the embodiments of the presentinvention. Apparently, the accompanying drawings in the followingdescription show merely some embodiments of the present invention, and aperson of ordinary skill in the art may still derive other drawings fromthese accompanying drawings without creative efforts.

FIG. 1 is a schematic architectural diagram of a communications systemaccording to an embodiment of the present invention;

FIG. 2 is a schematic flowchart of a method for measuring aninterference degree according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a CMTS according to anembodiment of the present invention;

FIG. 4 is a schematic structural diagram of another CMTS according to anembodiment of the present invention;

FIG. 5 is a schematic structural diagram of a CM according to anembodiment of the present invention;

FIG. 6 is a schematic structural diagram of another CM according to anembodiment of the present invention; and

FIG. 7 is a schematic structural diagram of a cable communicationssystem according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

To make the objectives, technical solutions, and advantages of theembodiments of the present invention clearer, the following clearlydescribes the technical solutions in the embodiments of the presentinvention with reference to the accompanying drawings in the embodimentsof the present invention. Apparently, the described embodiments are somebut not all of the embodiments of the present invention. All otherembodiments obtained by a person of ordinary skill in the art based onthe embodiments of the present invention without creative efforts shallfall within the protection scope of the present invention.

For ease of understanding, first, an example diagram of an overallsystem architecture of a cable communications system that can implementa method of the embodiments of the present invention is first described.It should be understood that the embodiments of the present inventionare not limited to a system architecture shown in FIG. 1. In addition,an apparatus in FIG. 1 may be hardware, or may be software divided basedon a function, or a structure of both software and hardware.

The system shown in FIG. 1 includes a cable modem termination system(CMTS) 110, a CM 120, a CM 130, a CM 140, and a CM 150. It should benoted that the CMTS and a quantity of CMs in FIG. 1 shall not beconstrued as a limitation on the present invention. The CMTS 110, the CM120, the CM 130, the CM 140, and the CM 150 may comply with theconventional Data Over Cable Service Interface Specifications (DOCSIS)3.1. A signal transmission direction from the CMTS to the CM is referredto as a downlink direction, and a signal transmission direction from theCM to the CMTS is referred to as an uplink direction.

The CMTS is a device that manages and controls CMs, and can beconfigured by using a console interface or an Ethernet interface.Configuration content of the CMTS mainly includes a downlink frequency,a downlink modulation scheme, a downlink level, and the like. Thedownlink frequency can be set to any value within a designated frequencyrange. To avoid interference with a signal of another channel, thedownlink frequency needs to be selected from specified frequencies withreference to a cable television channel division table. A modulationscheme should be selected in consideration of channel transmissionquality. In addition, Internet Protocol (IP) addresses of Dynamic HostConfiguration Protocol DHCP) and Trivial File Transfer Protocol (TFTP)servers, an IP address of the CMTS, and the like need to be set. Afterthe foregoing setting is completed, if an intermediate line is notfaulty and attenuation of a signal level meets a requirement, the DHCPand TFTP servers are started. In this way, a normal communicationchannel can be established between a front end and the CM.

The CM is a device that is on a cable television network (namely, acable network) and that is used to connect to the Internet. The CM isconnected in series between a cable television cable socket in a user'shome and an Internet access device. The other end connected to the CM byusing the cable television network is on a cable television station, andthe other end may be referred to as a front end or a head end.

A working mode of the CMTS 110 is CCFD. As shown in FIG. 1, the CMTS 110may separately use channels occupying a D1 spectrum, a D2 spectrum, anda D3 spectrum to send downlink signals, and may also receive uplinksignals sent by using channels occupying a U1 spectrum, a U2 spectrum,and a U3 spectrum. The D2 spectrum overlaps the U2 spectrum, and the D3spectrum overlaps the U3 spectrum. The CMTS may send signals with sameor different power to all CMs, and the CMTS may receive signals withsame or different power that are sent by the CMs.

The CM 120, the CM 130, the CM 140, and the CM 150 keep uplink anddownlink frequency division duplex FDD. The CM 120, the CM 130, the CM140, and the CM 150 need to be grouped based on a degree of interference(which may also be referred to as interference severity or mutualisolation). For example, the CM 120 and the CM 130 are in a same group,the CM 120 and the CM 130 may use channels occupying the U1 spectrum andthe U3 spectrum to send uplink signals, and may receive downlink signalssent by using channels occupying the D1 spectrum and the D2 spectrum.The U1 spectrum, the U3 spectrum, the D1 spectrum, and the D2 spectrumdo not overlap each other.

The CM 140 and the CM 150 are in a same group, the CM 140 and the CM 150may use channels occupying the U1 spectrum and the U2 spectrum to senduplink signals, and may receive downlink signals sent by using channelsoccupying the D1 spectrum and the D3 spectrum. The U1 spectrum, the U2spectrum, the D1 spectrum, and the D3 spectrum do not overlap eachother.

In this embodiment of the present invention, a degree of interferencebetween any two CMs, for example, two of M CMs connected to the CMTS,may be represented by CM_(i,j). Specifically, CM_(i,j) indicates adegree of interference of a signal sent by a j^(th) CM to a signalreceived by an i^(th) CM in the M CMs.

In addition, a current relatively common solution for testing aninterference degree is as follows: First, a CMTS allocates anuplink/downlink silent timeslot. In the silent timeslot, only onedesignated CM sends a probing signal, and other CMs can only receivesignals but cannot send signals. In addition, the CMTS stops sending adownlink signal in the silent timeslot, to avoid interference to theprobing signal sent by the designated CM. The other CMs obtain aninterference degree by calculating a difference between power of areceived probing signal and power of the probing signal sent by thedesignated CM.

However, in this test solution, all of the M CMs need to be designatedin turn to repeat the foregoing process. M operations need to beperformed to obtain an interference table of an entire network, and thistakes a relatively long time. In addition, during the foregoing testprocess, the CMTS needs to suspend sending of a downlink signal. Thisbelongs to lossy measurement.

FIG. 2 is a schematic flowchart of a method for measuring aninterference degree according to an embodiment of the present invention.It should be understood that FIG. 2 shows steps or operations of themethod, but these steps or operations are merely examples. In thisembodiment of the present invention, another operation may be performedor a variant of each operation in FIG. 2 may be performed. In addition,the steps in FIG. 2 may be performed in a sequence different from thatshown in FIG. 2, and not all operations in FIG. 2 need to be performed.

S210. A CMTS sends a broadcast message to all CMs connected to the CMTS,where the broadcast message includes information designating one of theCMs to send a probing signal by using a spectrum S in a timeslot T, andthe spectrum S is one of overlapping parts between uplink and downlinkspectrums.

The broadcast message may be in a format of a P-MAP message in theDOCSIS 3.1 standard, or may be in another message format, provided thatthe broadcast message includes information designating one of the CMs tosend a probing signal by using the spectrum S in the timeslot T.

S230. The CMTS broadcasts a pseudo random binary sequence (PRBS) byusing the spectrum S in a downlink direction in the timeslot T.

Specifically, after receiving the broadcast message sent by the CMTS,the designated CM sends a probing signal based on indication content byusing the designated spectrum S in an uplink direction in the timeslotT. At the same time, the CMTS sends the PRBS by using the spectrum S inthe downlink direction. It should be noted that the PRBS is a knownpseudo-random sequence and is not a service data signal.

Usually, power of the probing signal sent by the designated CM needs tobe lower, for example, 20 to 30 dB lower, than power of a sent uplinkservice data signal, to reduce interference to downlink signals of otherCMs.

S250. The CMTS obtains modulation error ratio (MER) information recordedin the timeslot T by other CMs, and uses a difference between MERinformation in the timeslot T and MER information in a normal datatimeslot, of each of the other CMs, as intensity of interference to thecorresponding CM, where the normal data timeslot is a timeslot in whichthe CMTS sends service data in the downlink direction.

The MER information is a logarithmic measurement result of signaldistortion, and is similar to a signal-to-noise ratio or acarrier-to-noise ratio of an analogue system. The obtained MERinformation recorded in the timeslot T by the other CMs can reflect asignal distortion status of each CM in a test environment. The testenvironment is that the designated CM sends a probing signal by usingthe designated spectrum S in the uplink direction, and the CMTSbroadcasts a PRBS by using the spectrum S in the downlink direction. MERinformation of each CM in the normal data timeslot can reflect a signaldistortion status in a normal service data receiving and sendingenvironments. Intensity of interference to each CM can be learned of byusing an MER difference between the foregoing two environments of eachof the other CMs.

The other CMs are CMs remaining after the designated CM is removed fromall the CMs connected to the CMTS, namely, non-designated CMs.

Alternatively, in an embodiment, the CMTS that “obtains MER informationrecorded in the timeslot T by other CMs, and uses a difference betweenMER information of each CM in the timeslot T and MER information in anormal data timeslot as intensity of interference to the correspondingCM” in step S250 may be replaced with another management device ormanagement module, provided that the another management device ormanagement module can exchange information with the CM, obtain the MERinformation recorded in the timeslot T by each CM, and completecomparison and computation of the MER information of each CM in thetimeslot T and the MER information in the normal data timeslot. Thisdoes not affect an implementation effect of this solution.

Further, in an embodiment, before step S250, the method further includesS240 (not shown in the figure): After receiving the broadcast messagesent by the CMTS, the other CMs record MERs when sending probing signalsby using the designated spectrum S in the designated timeslot T.

Furthermore, in an embodiment, the method further includes S270: TheCMTS groups, based on the obtained intensity of interference to each ofthe other CMs, a CM undergoing interference whose intensity is higherthan a threshold and the designated CM into a group. The threshold ispreset, and a specific value may be set according to an actual precisionrequirement and an empirical value.

Optionally, in an embodiment, the CMTS may further performclassification to obtain two spectrums: an uplink dedicated (US Only)spectrum and a downlink dedicated (DS Only) spectrum. In aninitialization phase, the CM obtains information about anuplink/downlink physical channel by using a channel corresponding to theDS only spectrum, and the information includes one or more items ofinformation such as a channel type (DOCSIS3.0 or DOCSIS3.1), a channelidentifier (ID), and a channel center frequency or a channel bandwidth.After being powered on, the CM completes ranging or registration byusing a channel corresponding to the US Only spectrum. The uplinkdedicated spectrum and the downlink dedicated spectrum that are obtainedthrough classification do not overlap. In addition, the CMTS maydetermine, based on historical configuration information, whether the CMhas been grouped.

It should be noted that the foregoing procedure is described startingfrom a scenario in which no CM has been grouped. In a scenario in whichsome CMs have been grouped, in comparison with the foregoing method, atest range is limited to ungrouped CMs, and other processes orrequirements are basically consistent with those described above.Details are as follows:

The CMTS may send a broadcast message to the ungrouped CMs, where thebroadcast message includes information designating one of the ungroupedCMs to send a probing signal by using a spectrum S′ in a timeslot T′,and the spectrum S′ is one of overlapping parts between uplink anddownlink spectrums. The designated CM sends a probing signal by usingthe designated spectrum S′ in an uplink direction in the timeslot T′.The CMTS sends a PRBS by using the spectrum S′ in the downlinkdirection. The CMTS obtains MER information recorded in the timeslot T′by non-designated CMs in the ungrouped CMs, and uses a differencebetween MER information in the timeslot T′ and MER information in anormal data timeslot, of each of the other CMs, as intensity ofinterference to the corresponding CM. Then, the CMTS groups CMs based onthe obtained interference intensity.

Different CMs and different spectrums on which the CMs send probingsignals are designated, and the foregoing process is repeated until allCMs are grouped. During specific implementation, all CMs may be groupedinto a grouped set and an ungrouped set, and the foregoing groupingprocess is repeated in the ungrouped set. After being grouped, a CM isremoved from the ungrouped set, until the ungrouped set is empty.

According to the solution of this embodiment, one designated CM isrequired to send a probing signal by using a designated spectrum in anuplink direction in a particular timeslot, and at the same time, theCMTS broadcasts a PRBS by using the designated spectrum in a downlinkdirection, to construct a test environment. A difference between an MERof each CM in the test environment and an MER in a normal service datareceiving and sending environment reflects intensity of interference toeach CM. In the constructed test environment, the CMTS also sends asignal, and this is nearer an actual normal service data receiving andsending environment. In this way, measured intensity of interference tothe CM is more accurate. In addition, CM grouping can be fast completeddirectly based on a magnitude relationship between the interference andthe threshold.

It should be noted that in this embodiment, the difference between theMER information of each CM in the non-designated CMs in the timeslot Tand the MER information in the normal data timeslot is used as theintensity of interference to the corresponding CM, that is, the MERinformation in the normal data timeslot is used as a reference value. Aperson of ordinary skill in the art should understand that a simplevariant of the normal data timeslot should also be construed as anembodiment of the present invention, for example, there is no limitationthat the normal data timeslot is a timeslot in which the CMTS sendsservice data in the downlink direction, but is a timeslot in whichspecific data similar to service data is sent.

An embodiment of the present invention provides a CMTS. As shown in FIG.3, the CMTS 300 includes a sending module 310, a processing module 320,and a receiving module 330.

The sending module 310 is configured to send a broadcast message to allCMs connected to the CMTS, where the broadcast message includesinformation designating one of the CMs to send a probing signal by usinga spectrum S in a timeslot T, and the spectrum S is one of overlappingparts between uplink and downlink spectrums; and is further configuredto broadcast a pseudo random binary sequence PRBS by using the spectrumS in a downlink direction in the timeslot T.

The receiving module 330 is configured to receive modulation error ratio(MER) information recorded in the timeslot T by other CMs.

The processing module 320 is configured to use, based on the modulationerror ratio MER information recorded in the timeslot T by the other CMsand obtained by the receiving module 330, a difference between MERinformation in the timeslot T and MER information in a normal datatimeslot, of each of the other CMs, as intensity of interference to thecorresponding CM.

The other CMs are CMs remaining after the designated CM is removed fromthe ungrouped CMs, namely, non-designated CMs. The normal data timeslotis a timeslot in which the CMTS sends service data in the downlinkdirection.

Further, in an embodiment, the CMTS 300 further includes a groupingmodule 340, configured to group, based on the intensity, obtained by theprocessing module, of interference to each of the other CMs, a CMundergoing interference whose intensity is higher than a threshold andthe designated CM into a group.

The processing module 320 may be a processor or a controller, or may bea general-purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field programmablegate array FPGA) or another programmable logic device, a transistorlogic device, a hardware component, or any combination thereof. Theprocessing module may implement or execute various example logicalblocks, modules, and circuits described with reference to contentdisclosed in the present invention. Alternatively, the processor may bea combination of processors implementing a computing function, forexample, a combination of one or more microprocessors, or a combinationof the DSP and a microprocessor. The receiving module 330 and thesending module 310 may be a receiving interface part and a sendinginterface part in a transceiver respectively, or may be a receivinginterface part and a sending interface part in a transceiver circuitrespectively.

According to the solution of this embodiment, one designated CM isrequired to send a probing signal by using a designated spectrum in anuplink direction in a particular timeslot, and at the same time, theCMTS broadcasts a PRBS by using the designated spectrum in a downlinkdirection, to construct a test environment. A difference between an MERof each CM in the test environment and an MER in a normal service datareceiving and sending environment reflects intensity of interference toeach CM. In the constructed test environment, the CMTS also sends asignal. In this way, measured intensity of interference to the CM ismore accurate. In addition, CM grouping can be fast completed directlybased on a magnitude relationship between the interference and thethreshold.

Another embodiment of the present invention provides another CMTS. TheCMTS has a schematic structural diagram the same as that shown in FIG.3, and also includes a sending module 310, a processing module 320, anda receiving module 330.

The sending module 310 is configured to send a broadcast message toungrouped CMs, where the broadcast message includes informationdesignating one of the ungrouped CMs to send a probing signal by using aspectrum S′ in a timeslot T′, where the spectrum S′ is one ofoverlapping parts between uplink and downlink spectrums; and is furtherconfigured to broadcast a pseudo random binary sequence PRBS by usingthe spectrum S′ in a downlink direction in the timeslot T′.

The receiving module 330 is configured to receive modulation error ratioMER information recorded in the timeslot T′ by other CMs.

The processing module 320 is configured to use, based on the MERinformation recorded in the timeslot T′ by the other CMs and obtained bythe receiving module 330, a difference between MER information in thetimeslot T′ and MER information in a normal data timeslot, of each ofthe other CMs, as intensity of interference to the corresponding CM.

The other CMs are CMs remaining after the designated CM is removed fromthe ungrouped CMs, and the normal data timeslot is a timeslot in whichthe CMTS sends service data in the downlink direction.

Further, in an embodiment, the CMTS 300 further includes a groupingmodule 340, configured to group, based on the intensity, obtained by theprocessing module, of interference to each of the other CMs, a CMundergoing interference whose intensity is higher than a threshold andthe designated CM into a group.

The processing module 320 may be further configured to determine, basedon configuration information of each CM connected to the CMTS, whetherthe CM belongs to the ungrouped CMs.

For description of functions of the modules in this embodiment, allrelated content of the steps in the foregoing method embodiment can becited. In addition, hardware implementation of the sending module 310,the processing module 320, and the receiving module 330 in thisembodiment is similar to that in the foregoing embodiment, and detailsare not described herein again.

FIG. 4 is a schematic structural diagram of a CMTS 400 according toanother embodiment of the present invention. The CMTS 400 includes amemory 410, a processor 420, a receiver 430, and a transmitter 440.

The memory 410 is configured to store a program.

The processor 420 is configured to execute the program stored in thememory 410.

When the processor 420 executes the program stored in the memory 410,the processor 420 is configured to invoke the transmitter 440 to: send abroadcast message to all CMs connected to the CMTS, where the broadcastmessage includes information designating one of the CMs to send aprobing signal by using a spectrum S in a timeslot T, and the spectrum Sis one of overlapping parts between uplink and downlink spectrums; andbroadcast a pseudo random binary sequence PRBS by using the spectrum Sin a downlink direction in the timeslot T. The processor 420 is furtherconfigured to invoke the receiver 430 to receive MER informationrecorded in the timeslot T by other CMs.

The processor 420 is further configured to calculate a differencebetween MER information in the timeslot T and MER information in anormal data timeslot, of each of the other CMs.

The other CMs are CMs remaining after the designated CM is removed fromall the CMs connected to the CMTS, and the normal data timeslot is atimeslot in which the CMTS sends service data in the downlink direction.

For description of functions of the modules in this embodiment, allrelated content of the steps in the foregoing method embodiment can becited, and details are not described herein again.

Another embodiment of the present invention provides another CMTS. TheCMTS has a schematic structural diagram the same as that shown in FIG.4, and includes a memory 410, a processor 420, a receiver 430, and atransmitter 440.

The memory 410 is configured to store a program.

The processor 420 is configured to execute the program stored in thememory 410.

When the processor 420 executes the program stored in the memory 410,the processor 420 is configured to invoke the transmitter 440 to: send abroadcast message to ungrouped CMs, where the broadcast message includesinformation designating one of the ungrouped CMs to send a probingsignal by using a spectrum S′ in a timeslot T′, and the spectrum S′ isone of overlapping parts between uplink and downlink spectrums; andbroadcast a pseudo random binary sequence PRBS by using the spectrum S′in a downlink direction in the timeslot T′. The processor 420 is furtherconfigured to invoke the receiver 430 to receive MER informationrecorded in the timeslot T′ by other CMs.

The processor 420 is further configured to calculate a differencebetween MER information in the timeslot T′ and MER information in anormal data timeslot, of each of the other CMs.

The other CMs are CMs remaining after the designated CM is removed fromthe ungrouped CMs, and the normal data timeslot is a timeslot in whichthe CMTS sends service data in the downlink direction.

The processor 420 is further configured to determine, based onconfiguration information of each CM, whether the CM belongs to theungrouped CMs.

For description of functions of the modules in this embodiment, allrelated content of the steps in the foregoing method embodiment can becited, and details are not described herein again.

Another embodiment of the present invention provides a cable modem CM.The CM has a schematic structural diagram shown in FIG. 5, and includesa sending module 510, a receiving module 520, and a recording module530.

The receiving module 520 is configured to receive a broadcast messagesent by a CMTS, where the broadcast message includes informationdesignating the CM to send a probing signal by using a spectrum S in atimeslot T, and the spectrum S is one of overlapping parts betweenuplink and downlink spectrums; and is further configured to receive, byusing the designated spectrum S in the designated timeslot T, a pseudorandom binary sequence PRBS sent by the CMTS.

The sending module 510 is configured to send a probing signal by usingthe designated spectrum S in the designated timeslot T based on thebroadcast message received by the receiving module 520.

The recording module 530 is configured to: record a local MER when aprobing signal is sent by using the designated spectrum S in thedesignated timeslot T, and record a local MER in a normal data timeslot.

Further, the sending module 510 is further configured to send the MERinformation recorded by the recording module 530 to the CMTS.Alternatively, the sending module 510 sends a difference between MERinformation in the timeslot T and MER information in the normal datatimeslot to the CMTS.

The recording module 530 may be implemented in terms of hardware byusing a combination of a control circuit and a storage circuit. Thecontrol circuit may be a processor or a controller, or may be ageneral-purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field programmablegate array (FPGA) or another programmable logic device, a transistorlogic device, a hardware component, or any combination thereof. Thereceiving module 520 and the sending module 510 may be a receivinginterface part and a sending interface part in a transceiverrespectively, or may be a receiving interface part and a sendinginterface part in a transceiver circuit respectively.

For description of functions of the modules in this embodiment, allrelated content of the steps in the foregoing method embodiment can becited, and details are not described herein again.

Another embodiment of the present invention provides another CM. The CMhas a schematic structural diagram shown in FIG. 6, and includes amemory 610, a processor 620, a receiver 630, and a transmitter 640.

The memory 610 is configured to store a program.

The processor 620 is configured to execute the program stored in thememory 610.

When the processor 620 executes the program stored in the memory 610,the processor 620 is configured to invoke the receiver 630 to: receive abroadcast message sent by a CMTS, where the broadcast message includesinformation designating the CM to send a probing signal by using aspectrum S in a timeslot T, and the spectrum S is one of overlappingparts between uplink and downlink spectrums; and is further configuredto receive, by using the designated spectrum S in the designatedtimeslot T, a pseudo random binary sequence PRBS sent by the CMTS.

The processor 620 is further configured to: invoke the transmitter 640to send a probing signal by using the spectrum S in the timeslot T; andinvoke the memory 610 to record a local MER by using the designatedspectrum S in the designated timeslot T, and record a local MER in anormal data timeslot.

The processor 620 is further configured to: calculate a differencebetween MER information in the timeslot T and MER information in thenormal data timeslot, of each of the other CMs; and invoke thetransmitter 640 to send the calculated difference to the CMTS.Alternatively, the processor 620 does not directly perform thecalculation but sends the recorded MERs to the CMTS, and the CMTSperforms the calculation.

For description of functions of the modules in this embodiment, allrelated content of the steps in the foregoing method embodiment can becited, and details are not described herein again.

FIG. 7 is a schematic structural diagram of a cable communicationssystem 700 according to an embodiment of the present invention. Itshould be understood that the communications system shown in FIG. 7 ismerely an example, and the communications system in this embodiment ofthe present invention may further include another device or unit, orinclude modules with functions similar to those of the devices in FIG.7.

The cable communications system 700 includes a CMTS 710 and a pluralityof CMs 720, where the CMTS 710 is the CMTS 300 shown in FIG. 3 or theCMTS 400 shown in FIG. 4, and the CM 720 is the CM 500 shown in FIG. 5.For brevity, details are not described herein again.

A person of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm steps may be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraint conditions ofthe technical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of the present invention.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the foregoing system, apparatus, and unit, refer to acorresponding process in the foregoing method embodiments, and detailsare not described herein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented through some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate, and parts displayed as units may or may not be physical units,may be located in one position, or may be distributed on a plurality ofnetwork units. Some or all of the units may be selected based on actualrequirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of the presentinvention may be integrated into one processing unit, or each of theunits may exist alone physically, or two or more units are integratedinto one unit.

When the functions are implemented in the form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer-readable storage medium. Based on such anunderstanding, the technical solutions of the present inventionessentially, or the part contributing to the prior art, or some of thetechnical solutions may be implemented in a form of a software product.The computer software product is stored in a storage medium, andincludes several instructions for instructing a computer device (whichmay be a personal computer, a server, or a network device) to performall or some of the steps of the methods described in the embodiments ofthe present invention. The foregoing storage medium includes: any mediumthat can store program code, such as a USB flash drive, a removable harddisk, a read-only memory (ROM), a random access memory (RAM), a magneticdisk, or an optical disc.

The foregoing descriptions are merely specific implementations of thepresent invention, but are not intended to limit the protection scope ofthe present invention. Any variation or replacement readily figured outby a person skilled in the art within the technical scope disclosed inthe present invention shall fall within the protection scope of thepresent invention. Therefore, the protection scope of the presentinvention shall be subject to the protection scope of the claims.

What is claimed is:
 1. A method for measuring interference to a cablemodem (CM), the method comprising: sending, by a cable modem terminationsystem (CMTS), a broadcast message to all CMs connected to the CMTS,wherein the broadcast message comprises information designating one ofthe CMs to send a probing signal by using a spectrum S in a timeslot T,and wherein the spectrum S is one of overlapping parts between uplinkand downlink spectrums; broadcasting, by the CMTS, a pseudo randombinary sequence by using the spectrum S in a downlink direction in thetimeslot T; and obtaining, by the CMTS, modulation error ratio (MER)information recorded in the timeslot T by other CMs, and using adifference between MER information in the timeslot T and MER informationin a normal data timeslot, of each of the other CMs, as intensity ofinterference to the corresponding CM, wherein the other CMs are CMsremaining after the designated CM is removed from all the CMs connectedto the CMTS, and wherein the normal data timeslot is a timeslot in whichthe CMTS sends service data in the downlink direction.
 2. The methodaccording to claim 1, wherein the method further comprises sending, bythe designated CM, a probing signal by using the designated spectrum Sin an uplink direction in the timeslot T.
 3. The method according toclaim 1, wherein the method further comprises grouping, by the CMTSbased on the obtained intensity of interference to each of the otherCMs, a CM undergoing interference whose intensity is higher than athreshold and the designated CM into a group.
 4. The method according toclaim 1, wherein the CMTS further performs classification to obtain anuplink dedicated spectrum and a downlink dedicated spectrum, wherein thedownlink dedicated spectrum is used by each CM connected to the CMTS toobtain information about an uplink/downlink physical channel, andwherein the uplink dedicated spectrum is used by each CM to performranging or registration.
 5. A method for measuring interference to acable modem (CM), comprising: sending, by a cable modem terminationsystem (CMTS), a broadcast message to ungrouped cable modems CMs,wherein the broadcast message comprises information designating one ofthe ungrouped CMs to send a probing signal by using a spectrum S′ in atimeslot T′, and wherein the spectrum S′ is one of overlapping partsbetween uplink and downlink spectrums; broadcasting, by the CMTS, apseudo random binary sequence by using the spectrum S′ in a downlinkdirection in the timeslot T′; and obtaining, by the CMTS, modulationerror ratio (MER) information recorded in the timeslot T′ bynon-designated CMs in the ungrouped CMs, and using a difference betweenMER information in the timeslot T′ and MER information in a normal datatimeslot, of each of the other CMs, as intensity of interference to thecorresponding CM, wherein the other CMs are CMs remaining after thedesignated CM is removed from the ungrouped CMs, and wherein the normaldata timeslot is a timeslot in which the CMTS sends service data in thedownlink direction.
 6. The method according to claim 5, wherein themethod further comprises sending, by the designated CM, a probing signalby using the designated spectrum S′ in an uplink direction in thetimeslot T′.
 7. The method according to claim 5, wherein the methodfurther comprises grouping, by the CMTS based on the obtained intensityof interference to each of the other CMs, a CM undergoing interferencewhose intensity is higher than a threshold and the designated CM into agroup.
 8. The method according to claim 5, wherein the CMTS determines,based on configuration information of each CM, whether the CM belongs tothe ungrouped CMs.
 9. A cable modem termination system (CMTS),comprising a receiver, a transmitter, a memory and at least oneprocessor, wherein the at least one processor is coupled to the memory,the receiver, and the transmitter, wherein the memory includesinstructions that when executed by the at least one processor cause theCMTS to perform the following: sending a broadcast message to ungroupedcable modems (CMs), wherein the broadcast message comprises informationdesignating one of the ungrouped CMs to send a probing signal by using aspectrum S′ in a timeslot T′, wherein the spectrum S′ is one ofoverlapping parts between uplink and downlink spectrums; broadcasting apseudo random binary sequence by using the spectrum S′ in a downlinkdirection in the timeslot T′; receiving modulation error ratio (MER)information recorded in the timeslot T′ by other CMs; and using, basedon the MER information recorded in the timeslot T′ by the other CMs andobtained by the receiving module, a difference between MER informationin the timeslot T′ and MER information in a normal data timeslot, ofeach of the other CMs, as intensity of interference to the correspondingCM, wherein the other CMs are CMs remaining after the designated CM isremoved from the ungrouped CMs, and wherein the normal data timeslot isa timeslot in which the CMTS sends service data in the downlinkdirection.
 10. The CMTS according to claim 9, further performinggrouping, based on the intensity, obtained by the at least oneprocessor, of interference to each of the other CMs, a CM undergoinginterference whose intensity is higher than a threshold and thedesignated CM into a group.
 11. The CMTS according to claim 9, furtherperforming determining, based on configuration information of each CM,whether the CM belongs to the ungrouped CMs.
 12. A cable communicationssystem, comprising a cable modem termination system (CMTS) and aplurality of cable modems (CMs), wherein the CMTS comprises a receiver,a transmitter, a memory and at least one processor, wherein the at leastone processor is coupled to the memory, the receiver, and thetransmitter, wherein the memory includes instructions that when executedby the at least one processor cause the CMTS to perform the following:sending a broadcast message to ungrouped cable modems (CMs), wherein thebroadcast message comprises information designating one of the ungroupedCMs to send a probing signal by using a spectrum S′ in a timeslot T′,wherein the spectrum S′ is one of overlapping parts between uplink anddownlink spectrums; broadcasting a pseudo random binary sequence byusing the spectrum S′ in a downlink direction in the timeslot T′;receiving modulation error ratio (MER) information recorded in thetimeslot T′ by other CMs; and using, based on the MER informationrecorded in the timeslot T′ by the other CMs and obtained by thereceiving module, a difference between MER information in the timeslotT′ and MER information in a normal data timeslot, of each of the otherCMs, as intensity of interference to the corresponding CM, wherein theother CMs are CMs remaining after the designated CM is removed from theungrouped CMs, and wherein the normal data timeslot is a timeslot inwhich the CMTS sends service data in the downlink direction.
 13. Thecable communications system of claim 12, wherein the CMTS furtherperforms grouping, based on the intensity, obtained by the at least oneprocessor, of interference to each of the other CMs, a CM undergoinginterference whose intensity is higher than a threshold and thedesignated CM into a group.
 14. The cable communications system of claim12, wherein the CMTS further performs determining, based onconfiguration information of each CM, whether the CM belongs to theungrouped CMs.